A seamless interface is the joining of two computer programs so that they appear to be one program with a single user interface . In sewing and other crafts, a seam is the place where two pieces of material are joined together. Often, the seam is visible; you often see the thread where two pieces of cloth are sewn together. In computer program development as in sewing, concealing the seam is often desirable so that the finished work looks like one object rather than two joined together. In programming, a seamless user interface often involves developing a back-end program that presents a single user interface that conceals the fact that what is behind the interface are a number of different programs written in different languages, at different times, and by different developers. With programming distributed among different computers in a network, it becomes important to screen the user from the location of the logic and the data behind the user interface. A common objective of any methodology for application integration and systems integration is a seamless user interface. The term is sometimes used loosely to mean that one program works with another one and the user can use both of them.
Seamless is somewhat similar to the term transparent . Both mean that the user of something is unburdened by having to see what went into making it.